Adjustable bedknives for reel-type lawnmowers are commonly known. It is the purpose of those mowers to have a slight clearance between the rotating cutting reel and the bedknife. The bedknife is commonly movable toward and away from the reel to present a cutting edge against which the reel rotates and thereby operates to cut the grass. The prior art is already aware of various adjustments for adjusting the bedknife relative to the reel and thus establish the desired clearance for optimum cutting. Examples of the prior art are found in U.S. Pat. Nos. 3,187,492 and 3,680,293 and 4,335,569 and 4,345,419. The first three of said patents show pivotally mounted bedknives controlled by threaded members to thereby be positioned with their cutting edges relative to the rotating reel. The last said patent shows a fixed bedknife with a movable reel and with a piston type of fluid dampener controlling the reel.
The present invention differs from the prior art in that it provides for a bedknife-to-reel adjustment system whereby the bedknife cutting edge can always be positioned at a desired specified small tolerance or clearance relative to the cutting edge of the reel itself. That is, the bedknife can be adjustably moved into actual contact with the reel cutting edge, and then there is an automatic further movement of the bedknife to attain the desired small clearance of the bedknife cutting edge with respect to the cutting edges of the reel, as desired. The small clearance is automatically attained by virtue of the mechanics of the adjustment system itself, and it need not be manually achieved, and it is therefore consistent and accurate. Still further, the small clearance can be controlled and set at determined magnitudes, and then it is again automatically attained according to the setting.
The present invention provides for an on-the-job adjustment or setting, in accordance with the desires of the operator. Also, the entire system is capable of releasing the bedknife when debris, such as sticks and stones, become lodged between the bedknife and the reel, and thereby avoid dulling or any damage to the cutting edges.
An important aspect of this invention is the provision of the adjustment system mentioned and whereby the adjustment is automatically achieved in a very small or minute dimension, such as 0.001 to 0.003 inches, to thus provide for the optimum adjustment and avoid excessive wear between the respective cutting edges and to yet assure that the grass will be well mowed.